JPS60130628A - Production of resol phenolic resin foam - Google Patents

Abstract

PURPOSE:To obtain the titled foam improved in moldability and decreased in heat conductivity, by foaming a specified resol phenolic resin by using an acid curing agent obtained by mixing p-phenolsulfonic acid with sulfuric acid. CONSTITUTION:A resol phenolic resin foam is obtained by foaming and curing a resol phenolic resin having reactivity in terms of the quantity of heat generated during curing of resin of 100 deg.C or below and a viscosity (25 deg.C)<=50P by using an acidic curing agent obtained by mixing p-phenolsulfonic acid with sulfuric acid at a weight ratio of 7:3-3:7. The resol resin used is obtained by condensing phenol with formaldehyde at a molar ratio of, usually, 1.4-1.8 in the presence of an alkali. In addition to the above acidic curing agent, a surfactant, blowing agent, plasticizer, flame retardant, etc., may be added to said phenolic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is aimed at obtaining a resol type phenolic resin foam (hereinafter referred to as phenol foam) molded product with high productivity, which has a small change over time, a low thermal conductivity, a small coefficient of linear expansion, and self-adhesion. Relating to a manufacturing method.

It is known that phenol foam obtained by foaming resol type phenol resin is superior to other plastic foams in terms of heat resistance and flame resistance. On the other hand, fire prevention regulations have recently been reviewed and stricter regulations are being considered, and even organic insulation materials, which have better insulation performance than inorganic insulation materials, are semi-nonflammable and have low smoke emission. is required to be. As a plastic foam that can satisfy this requirement, phenol foam is attracting attention as a heat insulating material for buildings, chemical plants, etc. In particular, urethane foam is currently the mainstream as a cold insulation material for chemical plants, but phenol foam has a lower linear expansion coefficient and superior flame resistance than urethane foam. Cold insulation work at plants is increasing. However, the thermal conductivity of conventional fluorocarbon foam is higher than that of urethane foam, and it is also disadvantageous in terms of moldability and processability.

As a result of repeated research aimed at reducing the thermal conductivity of phenol foam and improving its moldability, the present inventor discovered that it is possible to use a specific resol type phenolic resin and a specific acidic curing agent. found that these objectives could be solved by using a resol-type funol resin that has a temperature of 100°C or less and a viscosity of 50 voids or less at 25°C, p-tunolsulfonic acid, and sulfuric acid. This is a method for producing a non-norl foam, characterized by using an acidic curing agent mixed with a ratio of 7=3 to 3 near.

Phenol foam is generally produced by adding a surfactant, a low boiling point organic liquid, or an acid to a resol-type phenolic resin obtained by reacting phenol with form 7/l/f in the presence of an alkaline catalyst. By adding a blowing agent made of a substance such as an inorganic salt that generates gas when acting, and an acidic curing catalyst, curing proceeds with heat generation, and at the same time, the foam is formed by expansion due to the blowing agent.

Conventional foam foam has high thermal conductivity, and in order to make it as thermal conductive as urethane foam,...
Use a blowing agent with low thermal conductivity such as logenated hydrocarbons (
Methods using special surfactants and additives have been adopted, but in all cases, a high viscosity resol type Funol resin having a viscosity of 100 voids or more at 25°G, which will be described later, is used. However, whether
It is difficult to mix the resin sufficiently with the acidic curing agent, and large voids are created in the foam due to partial uncuring.

In addition, in order to obtain a sufficient stirring effect, high-speed stirring is required, which increases heat generation due to mechanical energy during stirring and causes turbulence in the bubbles. Moreover, the equipment cost for high-speed stirring is also expensive. The present inventors have discovered that the viscosity of the phenol resin at 25° C. must be 50 poise or higher in order to obtain a stable phenol foam with a uniform cell structure and no partial uncuring as described in 11 above.

On the other hand, the present inventor c. In order to reduce the thermal conductivity of phenol foam, since phenol foam with poor thermal conductivity mainly has an open cell structure, it is an essential condition to provide a sufficient closed cell structure. As a result of various studies with this in mind, we discovered that the reactivity of the Tuonol resin and the type of acidic curing agent greatly control the presence or absence of closed cells. In other words, it needs to be 1000G. fever is 1
If the temperature is 00°C, the cells will be destroyed and the closed cells will be lost no matter what kind of acidic curing agent is used. Furthermore, if the heat generation is too low, it will take a long time to complete curing and productivity will decrease. Even if a large amount of heat is supplied from the outside to compensate for this, it only accelerates the hardening near the surface of the molded product, but the interior is not sufficiently hardened, and the molded product obtained in this way Cell roughness near the surface is also severe, and the physical properties and appearance of this area deteriorate.

The heat generated during curing of the above resol type resin, that is, the reactivity, is as follows: 100 parts by weight of the resol type phenolic resin is
After stirring the resin into a milliliter container and bringing the temperature of the resin to 20°C, add 10 parts by weight of the acidic curing agent to be used for measurement and mix for about 10 seconds using a high-speed stirrer, leaving the thermometer inserted in the mixture. , the entire product is placed in an insulated container and cured, and is indicated by the maximum exothermic temperature reached at that time.

The resol type phenolic resin used in the present invention usually has a molar ratio of phenol and formaldehyde of 1 to 1.
The formaldehyde is used in an amount of 1.4 to 1.8 moles per mole, and is obtained by condensation reaction under alkalinity. The molar ratio of formaldehyde to phenol is 1.
4. Under lu, the reactivity of the two-nor resin produced is too high, which is undesirable in that closed cells are formed. If an attempt is made to lower the reactivity to below 100'C, the condensation of the thunol resin must proceed further, and as a result, the viscosity of the thunol resin becomes extremely high, and as mentioned above, the viscosity of the thunol resin becomes extremely high. Problems arise when mixing. In addition, if the molar ratio is 1.8 or more, the reactivity of the resulting Tuonol resin will decrease and it will take a long time to cure, and the concentration of free formaldehyde in the Tuonol resin will be high, so that the molded product cannot be molded into the mold after molding. When removed, there is a pungent odor of formaldehyde and the workability is also poor. The viscosity of the resol-type Funol resin must be 50 poise or less, preferably 20 to 50 poise, as measured at 25°C. If the viscosity is as low as 2O voids or less, sufficient cell film strength cannot be obtained during foaming, and the cell film tends to collapse and become open cells. Furthermore, if the viscosity is high, such as 50 poise or more, problems arise when mixing with the acidic curing agent, as described above. The viscosity of the above resin is JISK-6838
It is measured using a rotational viscometer specified in (Method for Measuring Viscosity of Adhesives).

As a result of investigating the use of various acidic curing agents normally used in the production of phenol foam for the resol-type phenolic resin described above, the present inventor found that p-phenolsulfonic acid, sulfuric acid, or a mixture of these two acids was used. It was confirmed that by using it as an acidic curing agent, it was possible to produce a phenol foam having a high closed cell ratio of 85 modulus or higher. However, although the closed cell structure of these phenolic foams having a high closed cell ratio is a necessary condition for lowering the thermal conductivity, it is not a sufficient condition. That is, in a case where p-phenolsulfonic acid or sulfuric acid was used alone as a curing agent, the closed cell ratio was 8.
Thermal conductivity does not necessarily decrease even after 5 p-
Only when tunolsulfonic acid and sulfuric acid are used in a mixture at a specific ratio, the thermal conductivity is lower than the value on the straight line connecting the individual thermal conductivities of p-phenolsulfonic acid and sulfuric acid, and the mixing ratio is It was found that the curve has a minimum value of thermal conductivity near 5=5 in terms of weight ratio. The thermal conductivity of the phenol foam produced at a mixing ratio of p-tunolsulfonic acid and sulfuric acid in the range of 7 = 3 to 3 nia by weight is 0.020 Kcal/mh'C or less, which is lower than the conventional one. Not only is the thermal conductivity lower than that of phenol foam, but it was also found to be stable with almost no change even after approximately one year.

The amount of acidic curing agent used in the present invention is 1
It is preferable that the amount is in the range of 8 to 15 parts by weight based on 0.00 parts by weight. If it is too small, curing will be slow and foaming will be insufficient, while if it is too large, the timing of foaming and curing will be different and a large stress will be generated in the foam. This will remain and cause cracks in the molded product immediately after demolding.

The resol type phenolic resin used in the present invention can contain the above-mentioned acidic curing agent and commonly used additives such as surfactants, blowing agents, plasticizers, and flame retardants. Typical examples of the surfactant include ethoxylated castor oil, dimethylpolysiloxane polyether bronok copolymer, oxyethylene oxypropylene bronok polymer, and the like. In addition, as a blowing agent, it is desirable to use rogenated hydrocarbons (with low thermal conductivity), especially 1. ．． 1. ．． 2-) Lichloro-1
, 2°2-trifluoroethane is optimal in terms of workability and the like.

In order to produce a phenol foam using a resol-type phenolic resin, an acidic curing agent, and the other additives mentioned above in the method of the present invention, a commonly used molding method for resol-type Founol foam can be used as is. The molding method is to stir and mix the resol-type phenolic resin with additives mixed in advance and the acidic curing agent, and then pour the mixture into a mold with an open top or a closed mold, and then foam and harden it. There is a batch-type production method in which the mixture is injected between the belts of a double-belt press having upper and lower belt conveyors, and a continuous production method in which plate-shaped foams are continuously produced. At this time, it is preferable to preheat the mold or belt to 60 to 80°C.

If this temperature is below 60°C, curing will be slow and the adhesion to the surface material will be poor when integrally molded with the surface material using a closed mold or double belt press. If the temperature is 80°C or higher, the bubbles tend to be disturbed and the closed cell ratio tends to decrease. Examples of surface materials on which the two-nor foam exhibits good adhesive properties when integrally molded by the method of the present invention include papers such as kraft paper, asphalt felt paper, and non-combustible treated paper, glass cloth, nonwoven fabric, and cotton canvas. There are many kinds of cloth. It also exhibits good adhesion to moisture-proof surface materials made of aluminum with a polyester film adhered to one side and a polyester nonwoven fabric adhered to the other side.

The characteristics of the phenol foam produced by the method of the present invention include firstly its low thermal conductivity and its small change over time.

In other words, changes in thermal conductivity over time are a phenomenon that can be observed not only in conventional two-north foam but also in plastic foam in general, and even urethane foam, which has the lowest thermal conductivity, has a high closed-cell structure. Nevertheless, changes in thermal conductivity over time are observed. Therefore, the above-mentioned characteristics of the phenolic foam obtained by the method of the present invention, such as low thermal conductivity and small change in thermal conductivity over time, are evaluated as providing a highly reliable heat insulating material with stable heat insulating performance. .

A second feature of the present invention is that it has a small coefficient of linear expansion.

That is, in the case of a cold insulation material for a low-temperature chemical plant, it is desirable that the coefficient of linear expansion of the cold insulation material is close to the coefficient of linear expansion of the metal that is the material that constitutes the tank and piping. Conventionally, the coefficient of linear expansion of the Two Nord foam, which has a high closed cell ratio, is 3.5X10.
/'C or more, but the coefficient of linear expansion of the two-knoll form according to the present invention is as small as 2.5×10 /°G, which can improve the reliability of the sealing part of the cold insulation material during cold insulation work.

A third feature of the present invention is that it has self-adhesive properties and has long moldability. In other words, the conventional method for manufacturing cold insulation materials using two-north foam is to first mold a block-shaped foam, then cut out plate-shaped or semi-cylindrical cold insulation materials, and then glue the surface material to this. However, with this method, the cut out surface becomes Founor foam il'? Yes 17) Due to its brittleness and powderiness, it has poor adhesion to the surface material, and even when integrally molded with the surface material that is foamed in a closed mold, it has poor self-adhesion with the surface material. The moldability was poor, such as the need to apply adhesive to the surface material in advance. However, when foaming in a mold using the resol type phenolic resin and acidic curing agent according to the present invention, self-adhesiveness during integral molding with the surface material was poor.

The present invention will be further explained below with reference to Examples.

Example 1 1.6 moles of formaldehyde per mole of phenol was mixed with 80% sodium hydroxide at a concentration of 40% by weight as a catalyst.
Condensation was performed at ~90°C to obtain a resol type phenolic resin (hereinafter abbreviated as resin A).

The properties of this resin are shown in Table 1.

To 100 parts by weight of resin A, 2 parts by weight of ethoxylated castor oil and 10 parts by weight of 1,1,2-)dichloro-1,,2,2-4 refluoroe 2F were mixed in advance, and to this was added 60 parts by weight of resin A.
An acidic curing agent prepared by mixing p-phenolsulfonic acid at a concentration of 60% by weight and sulfuric acid at a concentration of 60% by weight at a ratio of 5:5.
Add 0 parts by weight, mix with a high-speed stirrer, and preheat to 70°.
The mixture was poured into a closed mold of 30×30×10 mm heated to 70°C, and foamed and hardened in a 700°C curing furnace. The performance of the phenol foam molded product obtained by demolding after 20 minutes was measured and shown in Table 2.

Comparative Example 1 A resol type Funol resin (hereinafter abbreviated as Resin B) was obtained under the same conditions as in Example 1 using 1.2 mol of formaldehyde per 1 mol of phenol. The properties of this resin are -81
It was shown to.

A phenol foam molded article was obtained using the same recipe and method as in Example 1, except that resin A was changed to resin B. The performance of this molded product is shown in Table 2. Comparative Example 2 Resin B obtained in Comparative Example 1 was further condensed at 80 to 90'G to obtain a resol type Hunor resin (abbreviated as Resin C) with high viscosity. . The properties of this resin are shown in Table 1.

A phenol foam molded product was obtained using the same recipe and method as in Example 1, except that Resin A was changed to Resin C. However, striped uncured parts were observed throughout the interior of the molded product, and it was not a sample for evaluating performance. was not obtained.

Examples 2 to 4 and Comparative Examples 3 and 4 To 100 parts by weight of resin A, 2 parts by weight of ethoxylated castor oil and 13 parts by weight of 1,1.2) dichloro-1,2,2-1-lifluoroe 2F were mixed in advance. It was made into a resin liquid.

On the other hand, p-phenolsulfonic acid with a seismic intensity of 60% and sulfuric acid with a concentration of 60% by weight were mixed in a ratio of 10:0.7:3.
They were mixed at different ratios of 5:5 to 3near and 0:10 to obtain an acidic curing agent. We ordered the above two liquids, the resin liquid and the acidic curing agent, to 100 parts by weight of resin A and 10 parts by weight of the acidic curing agent.
The raw material liquid mixed in the foaming machine was supplied to the foaming machine (Model MTN IIJ), and the surface material (glass cloth for pipe side material, PETAL 100-25-N made by Nippon Vilene @) for exterior side material) was set in advance and heated to 70°C. Heated semi-cylindrical cold insulation mold (cold layer 160 m for 24 inch piping)
m) and foam-cured in a curing oven at 70'C.

The various performances of the obtained semi-cylindrical molded product are shown in Table 3.

Reference Examples 1 to 5 Using an acidic curing agent with a mixing ratio of 5:5 of p-tunolsulfonic acid with a concentration of 60% by weight and sulfuric acid with a concentration of 60% by weight, the mixing ratio of the resin liquid and the acidic curing agent was varied. A semi-cylindrical molded product of phenolphimeme was prepared by the same method as in Examples 2 to 4 and Comparative Example 3.4 except for the following changes. The mixing ratio of the resin liquid and the acidic curing agent was changed so that the amount of the acidic curing agent was 6.8, 10, 15.18 parts by weight per 00 parts by weight of the resin Al. The various performances of the obtained molded product are shown in Table 4.
Engineering S 2) J Hayashi-6838 (Adhesive viscosity measurement method) 3)
ASTM'D2856 Air Comparison Hydrometer Method 4) JIS
A1412 Flat plate comparison method 5) A, STM r) 696 6) Surface material peels off the next day 7) Curing is slow and the surface is soft. There were also some unfilled areas due to insufficient foaming 8) Cracks occurred in the molded product during demolding.

Patent applicant: Mitsui Toatsu Kagaku Taste Co., Ltd.

Claims (1)

[Claims] A resol type phenolic resin whose reactivity is 100°C or less as a calorific value when the resin is cured and whose viscosity at 25°C is 5o poise or less, p-phenolsulfonic acid and sulfuric acid in a ratio of 7:3 to 3 to 3. A method for producing a resol-type phenolic resin foam, characterized by using an acidic curing agent mixed at a weight ratio of 1.